There are different types of chain operators for windows, wherein a length of chain may be stored within a casing for the operator, and rotation of a drive sprocket within the casing causes movement of the chain either into or out of the casing for positioning of a window connected to an exposed end of the chain.
Examples of sprocket driven chain operators for windows are disclosed in U.S. Pat. Nos. 4,521,993; 4,481,735 and 4,014,136.
In particular, U.S. Pat. No. 4,521,993 to Tacheny et al., discloses a chain operator for a skylight window which includes a casing having a chain storage area. The chain storage area includes a chain guide track therein having a curved portion extending to a chain exit from the casing. A drive sprocket is mounted within the casing and is engagable with the chain. Connected to the drive sprocket is a drive means such as a hand crank or motor which converts a power input into rotation of the drive sprocket. Also, the casing is fitted with a unitary liner, preferably made of plastic, which as a first part for rotatably mounting the drive sprocket and a second part lining the curved portion of the guide track opposite the drive sprocket.
As in U.S. Pat. No. 4,521,993, most chains for use with chain operators are constructed from a plurality of solid links and a plurality of U-shaped links, with the U-shaped links being positioned in end-to-end abutting relation and the solid links having a thickness to closely fit within the U-shaped links. The links are constructed to provide substantial rigidity for the chain when it is in its extended configuration. This substantial rigidity allows the chain to transmit force in its extended configuration, to the window for opening and closing thereof. It is customary for the links to have coacting shapes to facilitate movement of the chain between straight and curved configurations while maximizing the strength thereof. It is also customary to form rivets with large heads pivotally interconnecting the opposite ends of a solid link to a pair of U-shaped links for increased strength.
However, despite the incorporation of the aforementioned structural features into chain operators, the loads to which such window operators are normally subjected especially in skylight applications, have caused (1) the drive sprocket of the window operator to wobble causing the jamming of sprocket teeth into chain links and (2) the chain to slip with respect to the sprocket teeth, to produce chatter and clunk noises as the chain is moved through the window operator. Such undesired consequences and limitations of the prior art operators have resulted from a number of inadequacies in the structure thereof, including the mounting of the drive sprocket, the guide structure for the chain, and the construction of the chain itself.
The disclosure and chain operator U.S. Pat. No. 4,521,993 to Tacheny et al. does not address or consider the problem of drive sprockets tending to wobble due to loading, and the chain producing chatter and clunk noises due to slippage as the chain is moved through the window operator.
In the past, measures have been taken to reduce the chatter and clunk noises produced by the chain, due to slippage and misalignment of chain links with drive sprocket teeth. Referring to FIGS. 7A and 7B, a guide projection having a shape of a solid mound is illustrated. As illustrated in FIG. 7B in particular, the solid mound-like guide projection is formed on the inside of the chain operator housing near the chain exit opening adjacent the window to which the free end of the chain assembly is connected. The purpose of this guide projection is to maintain the chain assembly 1 in alignment with the drive sprocket of a chain operator, as the chain passes through the same.
It has been discovered however, that with this guide projection design, the rivet heads may at times dig into the guide projection as the chain comes into contact with the guide projection. Also, the edges of the link plates may at times, dig into the surfaces of the projection over a short distance, slip out of the grooves formed therein, and consequently produce an annoying scraping and chatter noise which tends to reduce the quality of the chain operator's performance.
Accordingly, it is a primary object of the present invention to provide a chain operator for a window which prevents the drive sprocket from wobbling and avoids the jamming of sprocket teeth into chain links while eliminating chatter, scraping and clunk noise associated therewith.
It is another object of the present invention to provide a chain operator which maintains the chain links substantially in the plane of the planar surface of the drive sprocket as to avoid jamming of the sprocket teeth in the chain links.
It is a further object of the present invention to provide a chain operator which prevents the chain from slipping with respect to the sprocket teeth thereby eliminating the production of chatter and clunk noises as the chain is moved through the window operator.
Other and features objects will be explained hereinafter, and will be more particularly delineated in the appended claims, and hereinafter other objects of the present invention will, in fact, be apparent to those skilled in the art to which the present invention pertains.